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Volatile organic compounds (VOCs) are prevalent components of indoor air pollution. The photocatalytic degradation could be an interesting method to degrade them. This paper reports the photoactivity study of two classical nano-sized and two micro-sized commercial TiO 2 powdered samples. Photocatalytic tests have been performed following the degradation of acetone, acetaldehyde and toluene in the gas phase under UV light. An accurate study of the intermediate oxidation products was performed. XPS and FTIR analyses allowed to highlight the relationship between TiO 2 surface properties and reactivity toward VOCs explaining the different behavior of the photocatalyst in case of hydrophilic and hydrophobic pollutants.

The present work presents the results of 3D CFD combustion simulations of a current production 4-cylinder turbocharged Diesel engine using oxygen-enriched and humidified combustion air. Enriched Air (EA) is supposed to be produced by desorption from water, exploiting the different Henry constants of N2 and O2. Simulation results show that EA permits to increase the engine thermal efficiency (up to 10%) and drastically reduces soot emissions but increases in-cylinder peak pressure and NOx emissions. Combustion air humidification helps to reduce NOx increment, without losing the advantage in terms of thermal efficiency and in soot reduction, even if NOx emissions cannot be reported to the base case values.

New industrially produced photocatalytic tiles provide not only good photocatalytic performance, but also meet standard requirements with respect to hardness, lack of porosity, vitrified surface, durability. These characteristics were obtained mixing the photocatalytic materials with a commercial SiO2-based compound conventionally used to create vitrified surfaces. In the preparation, a commercial micro-TiO2 was used to avoid the use of traditional nanomaterials in powder form. Anatase form is maintained even after thermal treatments at 680 °C, as confirmed by both band gap and XRPD measurements on the final material. Photocatalytic degradation tests performed in water and air using methylene blue and NOx as a model pollutant, respectively, confirm the good performance of the tiles in both liquid and gas phase.

Mono (Ru or Co-based) and bimetallic (Co-Ru-based) silica supported catalysts have been prepared in order to evaluate the stability of metallic ruthenium after different thermal treatment. In all the samples the loading of cobalt is 10 wt% while the loading of ruthenium ranges from 0.5 to 10 wt%. Several analytic techniques (XRF, TGA, XRD, DRIFT) have been employed to shed light on the composition and the chemical-physical properties of prepared catalysts after calcination both in air or nitrogen atmosphere, in static environment or under dynamic flow. In particular, ruthenium resulted to be not stable in monometallic systems under calcination and air flow strongly favored the Ru loss. The behavior of bimetallic catalysts after thermal treatment was completely different thus indicating the role of cobalt as a stabilizer of metallic Ru phase probably due to the formation of a very stable spinel structure, as referenced in literature.

Downstream processing of biofuels and bio-based chemicals often represents the bottleneck for the economic sustainable development of new processes. It is also a challenging problem for process synthesis and optimization, due to the intrinsic nonideal thermodynamics of the liquid mixtures derived from the (bio)chemical conversion of biomass. In this Chapter, a recent mathematical framework is outlined for the structural and parameter optimization of process flowsheets with rigorous and detailed models. The optimization problem is formulated within the Generalized Disjunctive Programming (GDP) framework and the solution of the reformulated MINLP problem is approached with a decomposition strategy based on the Outer-Approximation algorithm. At first, the mathematical formulation and the numerical implementation are outlined. In the second portion of the Chapter, several validation examples in the field of biorefineries are proposed spanning from the economic optimization of single distillation columns, the dewatering task of diluted bio-mixtures, up to the distillation sequencing with simultaneous mixed-integer design of each distillation column for a quaternary mixture in the presence of azeotropes.

This chapter presents the use of a commercial micro-sized TiO2 powder as an alternative to the traditional nano-powders as semiconductors in photocatalytic processes. Results of the photocatalytic efficiency towards the photodegradation of the traditional pollutant molecules both in gas phase (nitrogen oxides (NOx) and volatile organic compounds (VOCs)) and in water phase (phenol) are presented and compared to the results obtained with two nano-sized reference powders. Micro-sized TiO2 is also industrially coated at the surfaces of porcelain gres tiles (Active Clean Air and Antibacterial Ceramic™). The possibility to have a photocatalytic material, strongly stuck at the surface of a vitrified tile, increases the use of photocatalysis in real conditions: no problem of filtration of the semiconductor from the liquid medium after use and no risks of leakage of nanoparticles in the atmosphere. Tests were performed using reactors equipped with UV-A lamps and with suitable analytical systems, depending on the final purpose. Characterization data from both powders and coated tiles are put in correlation with the photocatalytic results to understand the semiconductor action during the photocatalytic process. Polluting molecules were chosen in order to cover all the common aspects of environmental pollution: NOx and some VOCs represent the model molecules to test the efficiency of the micro-sized TiO2 (degradation from the pristine molecule to CO2 or inorganic salts) in gas phase. As for the water pollution, phenol was chosen as common pollutant in worldwide rivers. Moreover, tests on self-cleaning and antibacterial properties are also reported. The positive results of micro-sized TiO2 both in powder and coated onto the surface of porcelain gres tiles open the way to new photocatalytic products that do not make use of nanoscale powders avoiding problems to human safety caused by the inherent toxicity of the nanoparticles.

Micro-sized TiO

The sonochemical synthesis of nanostructured materials owes its origins to the extreme conditions created during acoustic cavitation, i.e., the formation of localized hot spots in the core of collapsing bubbles in a liquid irradiated with high intensity ultrasound (US). In particular, in the present work a sonochemical synthesis has been investigated for the production of three different iron-based samples supported on SiO2 and loaded with different metals and promoters (10 %wt of Fe; 30 %wt of Fe; 30 %wt of Fe, 2 %wt of K and 3.75 %wt of Cu) active in the Fischer-Tropsch (FT) process. Sonochemically synthesized heterogeneous catalysts were characterized by BET, XRPD, TPR, ICP, CHN, TEM, SEM and then tested in a fixed bed FT-bench-scale rig fed with a mixture of H2 and CO at a H2/CO molar ratio equal to 2, at activation temperatures of 350-400°C and reaction temperatures of 250-260°C. The experimental results showed that the ultrasonic samples are effective catalysts for the FT process. Notably, increasing the activation temperature increased CO conversion, while product selectivity did not diminish. All the sonochemically prepared samples presented in this work provided better catalytic results compared to the corresponding traditional FT impregnated catalysts.

Natural gas emissions contribute to climate change, and equally importantly, affect the health of populations near gas fields.[1] At night, the flares from the Bakken fields in North Dakota burn as bright as the lights in cities as large as Minneapolis. Rather than flaring (or worse, venting), this associated natural gas represents a multi-billion dollar opportunity.[2] Pipelines and liquefying natural gas are cost prohibitive in many cases. Converting methane to fuels is an attractive alternative. We examined three options to convert natural gas to syngas (H2 and CO), which is the first step to producing fuels: Steam Methane Reforming (SMR), Auto-Thermal Reforming (ATR), and Catalytic Partial Oxidation (CPOX). Based on a multi-objective optimization analysis, C5+ hydrocarbon yields are highest with CPOX as the first step followed by Fischer-Tropsch synthesis (FT). A micro-refinery with the CPOX-FT process treating 2800 kL·d−1 (100 MCF·d−1) natural gas, produces 1300 L·d−1 (8.2 bbl·d−1) of C5+ hydrocarbons. Maximum yields for the SMR-FT and ATR-FT processes are 938 L·d−1 and 1100 L·d−1 (5.9 bbl·d−1, 7.0 bbl·d−1) of C5+, respectively. Large-scale POX and ATR processes produce 1600 L per 2800 kL (10 bbl per 100 MCF) of natural gas.

Biomass-to-liquid Fischer-Tropsch (FT) is an industrial process that converts bio-syngas in hydrocarbons ranging from C 1 to C 100 . Bio-syngas, a syngas mixture produced from biomass, is characterized by a H 2 /CO molar ratio in the range 1.0–1.5. An iron-based catalyst supported on silica for CO hydrogenation with 30 wt% of metal was prepared, characterized by BET, SEM, TEM, TPR, XRD and tested at different temperatures and H 2 /CO ratios in a FT bench scale plant using a Packed Bed Reactor (PBR). The experimental results demonstrated that this catalyst is suitable for low H 2 /CO ratios, since by increasing the inlet H 2 /CO ratio the CO conversion increases, the product selectivity remains largely unchanged. Moreover the catalyst shows a satisfactory stability as a function of time of stream (TOS). A nonlinear regression was performed based on a selected kinetic model in order to obtain the main kinetic parameters. The elaborated kinetic model is based on the hypothesis that both FT and Water Gas Shift (WGS) reactions are active on the catalyst. Initially the regression was performed using MATLAB®, but the algorithm could not lead to an acceptable solution because of the high number of local minima presented by the objective function. In order to overcome this problem, a procedure in C++ has been developed. Respect to the model found in the literature, this new one has been rearranged for minimizing the multicollinearities between the optimized parameters and a satisfactory fitting respect the experimental values has been achieved. Based on the experimental collected data and the regressed parameters, a rigorous multi-scale simulation of reactor behaviour was developed in order predict the reactor yield and conversion.

A laboratory experience concerning a continuous distillation column for Industrial Chemistry and Chemical Engineering students is presented. The experience is based on practical exercise of the column running at infinite and finite reflux and on the elaboration of the collected data by both classical equations and computer simulation. The comparison between experimental and simulated data will help students to understand the theoretical basis of the distillation columns and the importance of a right representation of the phase equilibria representation. The mixture used as example in this work is a binary one of toluene and N-heptane.

The paper illustrates the redefinition of the concept of biorefinery and its application onto the biogas field. The proposed integrated framework merges in a synergistic way the second and third generation biorefineries with the aim of reducing the CO 2 emissions and maximizing the utilization of biomass potential. The specific focus of the paper is on the mathematical modelling of the main conversion steps of the lignocellulosic residuals into biosyngas by means of thermal treatment (pyrolysis, combustion, gasification) and, next, into biomethanol (heterogeneously catalyzed synthesis). The models are implemented in user-friendly programmes and adopted to estimate biomass conversion and process yield. A final study of sensitivity analysis is provided to open the way for the next process optimization based on detail models.

Flame spray pyrolysis (FSP) is an innovative and scalable technique, used to synthesize monometallic and bimetallic Co-Ru catalysts with 5% wt. Co, 10% wt. Co and 0.4% wt. Ru supported on SiO 2 active in the Gas-to-Liquids (GTL)-Fischer-Tropsch (FT) process, which converts syngas to hydrocarbons. The catalysts were characterized by TEM, FE-SEM-EDX, TPR, XRD and N 2 adsorption/desorption. All the three samples have been tested in a fixed bed FT-bench scale plant. Results demonstrated that the 5% wt. Co catalyst was not active toward FT synthesis, while samples containing 10% wt. Co and 10% wt. Co - 0.4% wt. Ru were suitable candidates for the GTL-FT process. With an increase in temperature, the CO conversion increased, the product selectivity remained unchanged, and the 10% wt. Co catalyst showed higher stability as a function of time-on-stream (TOS) with respect to traditionally prepared materials. The addition of 0.4% wt. of Ru improved the performance in terms of CO conversion and C 2+ yield.

The importance of the choice of a suitable substrate as supporting material for photoactive TiO2, either in the form of powders or thin films or in photoactive paints, is frequently disregarded. In this paper four different supports (stainless steel, sand-blasted stainless steel, Teflon and glass) are object of investigation. The final aim is to verify the presence of interactions between the photocatalyst (AEROXIDE® TiO2 P25 by Evonik Degussa Corporation) and the support, directly involved in the photocatalytic activity in the NOx abatement. The characterization results have been correlated with the photoactivity of the different samples. In particular, a coating of about 6–9 μm seems to allow a photocatalytic result free from any positive or negative interference with the supporting material, therefore giving reliable results about the photoactivity of the TiO2 under investigation.

The most important drawback of the use of TiO2 as photocatalyst is its lack of activity under visible light. To overcome this problem, the surface modification of commercial micro-sized TiO2 by means of high-energy ultrasound (US), employing CuCl2 as precursor molecule to obtain both metallic copper as well as copper oxides species at the TiO2 surface, is here. We have prepared samples with different copper content, in order to evaluate its impact on the photocatalytic performances of the semiconductor, and studied in particular the photodegradation in the gas phase of some volatile organic molecules (VOCs), namely acetone and acetaldehyde. We used a LED lamp in order to have only the contribution of the visible wavelengths to the TiO2 activation (typical LED lights have no emission in the UV region). We employed several techniques (i.e., HR-TEM, XRD, FT-IR and UV-Vis) in order to characterize the prepared samples, thus evidencing different sample morphologies as a function of the various copper content, with a coherent correlation between them and the photocatalytic results. Firstly, we demonstrated the possibility to use US to modify the TiO2, even when it is commercial and micro-sized as well; secondly, by avoiding completely the UV irradiation, we confirmed that pure TiO2 is not activated by visible light. On the other hand, we showed that copper metal and metal oxides nanoparticles strongly and positively affect its photocatalytic activity.

Nitrogen oxides (NO x ) play a key role in the atmospheric reactions that create ground-level ozone and acid rain. The exploitation of building coatings acting as catalysts for NO x degradation under the effect of solar radiation represents a feasible way of wide applicability to lower NO x concentration in air. A crucial issue for the practical application of photocatalytic coatings is the actual lifetime of the active material. To investigate this aspect, two paints and two plasters (silicate and siloxane resins based) commercially available were formulated with 2% TiO2 Aeroxide P25 and tested in the photocatalytic removal of NO x in air. The results collected over 1 year show how the photoactivity lifetime of these products always decreases with their curing age, being strictly correlated to the formulation of the materials.

Bisphenol A is an endocrine disruptor. Complete mineralization of bisphenol A is therefore a primary environmental issue. Here, the combination of ozonation and photocatalysis by TiO2 is proposed for the degradation and final mineralization of bisphenol A. TiO2 films deposited onto two sides of an Al lamina show good stability and high surface roughness. We used a specific experimental setup employing two facing ultraviolet lamps and TiO2 layers, together with an ozone flux. High-performance liquid chromatography–mass spectrometry determinations on bisphenol A solutions sampled at different reaction times and Fourier Transform Infrared analyses of the oxide at the end of the reaction were performed to study the reaction intermediates and the overall degradation mechanism. Our results show that pollutant mineralization achieved with the combined method is far higher, of 55% in the case of 0.3 mM bisphenol A, than those obtained by individual treatments such as photolysis (

This paper addresses the analysis and design of the transmission control system for a high-power power-shift agricultural tractor. Specifically, all the criticalities involved with the correct management of both single clutch and double clutch gear shifts are investigated, and a control system capable of providing good shifting performance in all operating conditions is proposed. Further, to comply with components tolerances and spreads in the production line, an automatic procedure for the end-of-line tuning of the transmission control system is proposed to objectively classify the quality of the gear shift and automatically optimize it. The suitability of the proposed approach is thoroughly tested on an instrumented vehicle.

Deacidification of crude vegetable oils containing high amounts of free fatty acids is the first step toward low-cost biodiesel production. In order to lower the acid content, the most popular method is based on an esterification process carried out with methanol and using Amberlysts as solid acid heterogeneous catalysts. This process was deeply investigated in recent years with good results. At the moment, the lifetime of the catalyst is the most crucial issue in industrial applications. With the aim of investigating this aspect, 90 consecutive batch deacidification runs, each lasting 6 h, were conducted using crude palm oil or soybean oil as a feedstock and Amberlyst 46 as a catalyst. At the end of the recycles, a decrease of activity of about 25% was observed, probably ascribed to some fragmentation of the catalyst’s particles, with a loss of active material, caused by the mechanical stress occurring in the batch reactor. The same reaction was also conducted in both continuous and semicontinuous cataly...

An esterification process is proposed to lower Free Fatty Acids (FFA) content in waste animal fat using solid acid ion exchange resins as catalysts. The final aim is to make this material a suitable feedstock for biodiesel production. Its exploitation does not interfere with the food chain, besides allowing to lower biodiesel production costs.

The photocatalytic activity of both commercial and homemade N-doped TiO2 samples, prepared at different pH from TiCl3 solutions, was tested for the degradation of toluene in the gas phase by using a solar irradiation source. Highest degradations and corresponding kinetic constants were achieved in the case of N-doped samples prepared at higher pH. Various adsorbed aromatic species (benzoic acid, the major surface product, benzylic alcohol, benzaldehyde) were observed at the surface of the exhaust catalysts by using FTIR-ATR spectroscopy. The trend of the photocatalytic efficiency in the visible region is discussed with respect to structural (XRD), morphological (BET, TEM), surface (XPS) and paramagnetic (EPR) characterization.

Iron-based catalysts supported on silica for CO hydrogenation with high amounts of metal (10–50%wt) have been prepared, characterized by BET and SEM and tested. CO conversion and yield to hydrocarbons increase with iron content in catalysts. Depending on the operative conditions Water Gas Shift (WGS) becomes a competitive reaction towards Fischer Tropsch (FT) synthesis. The activation energies values highlight the presence of two different chemical regimes. In particular, for 483 T T 2 by WGS becomes the predominant reaction.

The rate of 1,4-dichlorobenzene (1,4-DCB) degradation and mineralization in the aqueous phase was investigated either under direct photolysis or photocatalysis in the presence of commercial or sol-gel synthesized TiO2, or under sonolysis at 20 kHz with different power inputs. Two lamps, both emitting in the 340-400 nm wavelength range with different energy, were employed as irradiation sources. Photocatalysis ensured faster removal of 1,4-DCB with respect to sonolysis and direct photolysis. The highest degradation and mineralization rate was attained with the combined use of photocatalysis and sonolysis, i.e. under sonophotocatalytic conditions. The efficiency of the employed advanced oxidation techniques in 1,4-DCB degradation is discussed also in relation to their energy consumption, which might be decisive for their practical application.

Ultrasound (US) "pre-sonication effect" is the beneficial effect of US in the hydrolytic polymerization of epsilon-caprolactam (CL) mixtures with very low water concentrations (about 0.1-1 wt%). It appears after a mild initial treatment of the mixtures with US [17.5-20 kHz, short times (5-15 min), low temperatures (70-110 degrees C)] followed by heating at 220-260 degrees C. An explanation is proposed on the basis of the formation in mild conditions (100 degrees C) of low concentrations of cyclic oligomers never detected in the literature at those conditions. These, under US irradiation, produce linear amino acid oligomers, which are strong activators of polymerization when the mixture of CL and water, after US irradiation, is heated at the suitable polymerization temperature indicated above.

Epsilon-caprolactam (CL) polymerization to polyamide-6 (Nylon 6) was studied at different contents of water in CL (0.01-2 wt%), with or without epsilon-amino-caproic acid (ACA) as an activator, applying to the mixture an initial treatment of Ultrasound (US) (17.5-20 kHz) at low temperatures (70-110 degrees C) and for short times (max 10 min). It was verified that polymerization at 260 degrees C produces a polymer having a much higher molecular weight (MW) when US is applied with respect to silent (SIL) conditions i.e. without the use of ultrasound. This constitutes a "pre-sonication effect". The ratio (MW)(US)/(MW)(SIL) is inversely proportional to the initial content of water in CL. The action of US converts CL at very low temperatures (70-110 degrees C) and water content, in comparison with silent conditions where CL was unconverted. Optimized conditions are studied with respect to nature and pressure of gas inside the reactor, temperature, time and frequency of US irradiation, energy consumption and nature of activator.

Anatase−brookite composite nanocrystals were synthesized successfully by a controlled sol−gel reaction followed by a prolonged hydrothermal aging or by mild calcinations (300 and 450 °C). The physicochemical and photocatalytic properties of the synthesized TiO2 composites were studied along with several commercially available nanocrystalline TiO2 samples showing different features. Rietveld refinements of the powder X-ray diffraction pattern were used to track the brookite content systematically and to generally assess the phase composition of the different samples and their crystallite sizes. SEM, TEM, and HRTEM were used to characterize the particle morphology, size, and surface faceting. BET/BJH analyses combined with mercury porosimetry determinations were employed to characterize the surface area, porosity, and pore size distribution. The surface state of the TiO2 samples was analyzed by XPS by studying, in detail, the region of oxygen 1s to produce the OH/Otot surface ratio. The photocatalytic activ...

The esterification of diluted acetic acid with pure 2-ethyl-1-hexanol is a purification process, involving a liquid–liquid–solid catalyst system, where streams of water containing small amount of acid are purified and the acetic acid is converted to a high commercial value ester at the same time. This process has been studied in a wide range of acetic acid (AA) concentration (6–15%, w/w). A maximum final conversion of 67% can be reached at 372 K. A mathematical model is here proposed: this takes into account all the diffusional and reactive steps between the aqueous and organic phases and from the latter into the pores of the solid catalyst. The relative importance of the different steps is fully discussed.

The photoabatement of perfluorooctanoic acid in aqueous solution has been performed with a commercial nano-sized TiO2-based photocatalyst content of 0.66 g/L under an UV irradiation of 95 W/m(2). PFOA degradation intermediates were investigated by HPLC-MS and F-19-NMR analysis. Evidences of a degradation mechanism based on two competitive pathways are discussed: photo-redox and beta-scission pathways. Shorter perfluorinated carboxylic acids, CnF2n+1 COOH (n = 1-6), as expected degradation intermediates, were identified and their concentration trends over time were determined. The apparent pseudo-first order kinetic constant expressed as rate of PFOA disappearance was also measured: k(app)0.1296 h(-1). The influence of fluoride ions on TiO2 surface was analyzed by XPS technique, revealing a surface modification that affects the performances of the catalyst. (C) 2014 Elsevier B.V. All rights reserved.

With TiO2-photocatalysis being an effective alternative to other more expensive Advanced Oxidation Processes (AOPs), the possibility of using micro-sized TiO2 materials rather than the well-known nano-sized powders is an important goal in terms of both handling safety and cost saving. In this work the photodegradation of ethanol, used as a model VOC (Volatile Organic Compound) molecule, was investigated, comparing the efficiency of both commercial nano- and micro- sized TiO2 samples. In all cases the same degradation pathway was observed, namely, a consecutive first-order reaction with acetaldehyde as an intermediate product and CO2 and water as the final products. All photocatalysts were characterized by means of XRD, TEM, IR, BET and XPS analysis. A kinetic model was also developed considering the collected experimental data and a regression of both adsorption and kinetic constants was made using MATLAB software. The optimized parameters were used for simulating the experimental data using an ode15s algorithm.

Although the TiO2 is one of the most promising materials for its photocatalytic potential related to the pollution abatement, it strongly suffers from the low photocatalytic activity if it is used under visible light and not under UV light. Among the various possible modifications, the surface decoration with metal or metal oxides NPs can be a good strategy to increase the potential of TiO2 in the visible range. In this paper, a sonochemical method that exploits the use of high-energy ultrasounds is suggested to obtain this surface decoration. The support is a commercial and micrometric TiO2, cheaper and easier to handling than the nanometric P25. Samples were tested on the photodegradation of toluene and acetone in a gas phase system, using both the UV and LED lamp.

The biomass-to-liquid Fischer-Tropsch (FT) process is an industrial process that converts bio-syngas in hydrocarbons ranging from C1–C100. Bio-syngas, a syngas mixture produced from biomass, is characterized by a H2/CO molar ratio in the range 1.0–1.5. An iron-based catalyst supported on silica for CO hydrogenation with 30 g/g of metal was prepared, characterized by BET, SEM, TEM, TPR, XRD and tested at different temperatures and H2/CO ratios in a FT bench scale plant using a Packed Bed Reactor (PBR). The experimental results demonstrated that this catalyst is also suitable for low H2/CO ratios, since by increasing the inlet H2/CO ratio, the CO conversion increases, the product selectivity remains largely unchanged, and the catalyst shows a satisfactory stability as a function of time of stream (TOS). Based on the collected data, a rigorous multi-scale simulation of reactor behaviour was developed in order to support the experimental tests and predict the reactor yield and conversion. The elaborated kinetic model is based on the hypothesis that both FT and Water Gas Shift (WGS) reactions are active on the catalyst, and the calculated results agree with the obtained experimental data.

Biodiesel production could be economically sustainable if raw oils, i.e., waste cooking oil or oils with a high acid content, are used for its production. However, the high content of free fatty acid (FFA) of these oils makes necessary a pretreatment before the transesterification step. Esterification using methanol and a heterogeneous catalyst should be very convenient because this reaction permits to decrease FFA content by producing simultaneously methyl esters, i.e., biodiesel. This technology was applied in a continuous packed bed reactor for the deacidification of sunflower oil, using Amberlyst 46 as heterogeneous acid catalyst at pressure of 6 bar and temperature in the range of 54–95 °C. An amount of methanol five times greater than the stoichiometric was added to sunflower oil, in order to shift the reaction equilibrium but avoiding the formation of a double liquid phase. Two different kinetic models were considered: a pseudo-homogeneous and an adsorption based, which accounts for the different affinities toward the polymeric matrix of all the species involved in the reaction and the solvent (triglycerides). For both the models, either the ideal or non-ideal behavior of the mixture was considered, and the results were compared. The kinetic parameters of the esterification of free fatty acid were regressed using a robust mathematical model and using equilibrated resins, i.e., all the experiments started only after having let the catalyst adsorb reactants and products at the operative conditions.

An advanced model-based strategy for the online optimization and/or optimal control of (fed-)batch systems, the BSMBO&C, is applied to discontinuous equipment that can be subject to runaway phenomena. The aim is that of showing that it is simultaneously possible to provide profitable online optimization and/or optimal control policies, predict possible future hazardous situations in advance and automatically decide whether and when to (optimally) stop a production cycle in order to prevent safety risks (unavoidable runaways). All these actions are performed online, thus allowing for the effect of any external perturbation. A fed-batch process based on a well-known example of runaway reaction, i.e. the oxidation of 2-octanol to 2-octanone with nitric acid in aqueous solution, is selected as a benchmark to test the real attainability of simultaneous process profitability and safety.

A numerical modeling study on the low-temperature steam gasification process is presented to outline the possibility to drive the process with an integrated Concentrated Solar Power (CSP) plant, which provides low-temperature steam, with the aim of preserving a comparable efficiency of the new plant with traditional high-temperature biomass gasification processes. To meet this, the effective parameters and operating conditions are assessed and determined for low-temperature biomass gasification by means of sensitivity analysis, in order to find out the optimal design of the new gasifier. Crucial parameters comprise the residence time of the solid fuel and of the gas phase (leading to efficient gas–solid interactions), as well as the amount of injected oxygen and steam. Moreover, several operative parameters such as content of moisture in the biomass feedstock, size of the solid particles, equivalence ratio and structural components amount in the biomass feedstock are taken into account to optimize the operation. The molar ratio of H2/CO has been selected as a benchmark of efficiency in the process because the produced syngas would be applied in the methanol synthesis process, which needs a molar ratio of H2/CO close to the value of two. The percentage of the solid residue (weight % of the solid feedstock) has been evaluated along with the molar ratio of H2/CO in the low-temperature process to guide the re-design of the solar driven gasifier, in terms of reactor volume and amount of required oxygen and steam, which are necessary to sustain the process. The modeling and simulation to design the process have been accomplished by a comprehensive modeling package (GASDS), which includes kinetics of biomass devolatilization and pyrolysis, gasification, and secondary gas phase kinetic schemes. The gasifier, owing to its intrinsic multi-scale nature, is simulated describing both the particle and the reactor scales.

Gasification is a thermochemical process devoted to the production of syngas, starting from a solid fuel such as coal, biomass, or refuse-derived fuel (RDF). The gasification efficiency and the chemical composition of the produced syngas are strongly affected by the feedstock and the operating conditions of the process. Besides the direct use as a fuel for power generation, downstream applications of syngas for chemical production demand specific H2/CO ratios, as extensively reported in the literature. For this reason, in the present work, a comprehensive mechanistic approach is applied to the description of the coal gasification process, highlighting the sensitivity of key operating parameters on syngas quality. The solution of this multi-scale, multi-phase, and multi-component problem requires careful attention to the kinetics in the solid and the gas phase as well as the heterogeneous gas-solid reactions. The kinetic model is validated with experimental data obtained in updraft gasifiers (including the Sotacarbo pilot gasification plant), and the catalytic effects of ash on the reactivity of low-rank coals are also addressed and quantified. © 2015 American Chemical Society.

Water gas shift is a well-known reaction in which carbon monoxide reacts with steam to give carbon dioxide and hydrogen, representing an important step in the industrial production of hydrogen. The main role of this reaction is to increase the hydrogen content in the feed for the production of bulk chemicals such as methanol, ammonia, and hydrocarbons. It is today a crucial step in all of the thermochemical and catalytic technologies involved in the “biomass to liquid” processes. Water gas shift is an equilibrium-limited reaction moderately exothermic and favored at lower temperature, but in this condition it requires a suitable catalytic system, being limited by kinetic reasons. It is typically performed in conventional reactors via a two-stage process: a high-temperature shift (typically 643–673 K, 10–60 bar) and a low-temperature shift (∼473 K, 10–40 bar). The first step is catalyzed by an iron oxide/chromium catalyst whereas in the second stage it is promoted by using a catalyst based on Cu/ZnO(Al2O3). In the Fischer–Tropsch reactors catalyzed by iron catalyst, water gas shift is a parallel reaction and two different chemical regimes can be observed depending on the operative conditions. An alternative device for generating high-grade hydrogen from the water gas shift reaction is the membrane reactor. This chapter analyzes and resumes the recent advancements in the water gas shift reaction in membrane reactors, paying particular attention to hydrogen-selective membrane utilization for high-temperature applications.

Artificial photosynthesis is an up to date topic for the fixation of CO2 in form of valuable fuels. Recently, we set up an innovative concept of photoreactor to be applied to CO2 photoreduction, enabling operation up to 20 bar. This allows to improve CO2 solubility and to explore unconventional operating conditions for this very challenging reaction. Following a preliminary communication, to demonstrate the validity of the approach systematic testing has been here carried out on different TiO2 photocatalysts (anatase, rutile and anatase + rutile) doped with 0.1 wt% Au, by tuning pressure, temperature and pH. The operating conditions have been selected to maximise the production of gas phase products, i.e. CH4 + H2, with respect to liquid phase organic compounds. The present results overperform many of the recent achievements reported in the literature and throw the basis for a further optimisation of the photocatalytic material and of the photoreactor.

The influence of oxygen in the photocatalytic oxidation of perfluorooctanoic acid (PFOA) promoted by a commercial nano-sized titanium dioxide was studied by testing the reaction in different conditions: static air, oxygen flux, nitrogen flux and pre-saturated nitrogen flux. The reaction was monitored by Total Organic Carbon (TOC) analysis and Ionic Chromatography (IC). Shorter chain perfluorocarboxylic acids (PFCAs; C-n, n = 1-7) intermediate degradation products were quantitatively determined by High-Performance Liquid Chromatography combined with Mass Spectrometry (HPLC-MS) analysis. The presence of shorter chain PFCAs in solution was also monitored by F-19 NMR. The experimental findings are in agreement with two major oxidative pathways: C-n -> Cn-1 photo-redox and beta-scissions routes mediated by COF2 elimination. Depending on the experimental conditions, the mutually operating mechanisms could be unbalanced up to the complete predominance of one pathway over the other. In particular, the existence of the beta-scissions route with COF2 elimination was corroborated by the isolation and characterization of carbonyl difluoride, a predicted fluorinated decomposition by-product. (C) 2015 Elsevier B.V. All rights reserved.

Fixed bed reactors are frequently used for many catalytic reactions, but the difficult to remove the reaction heat in highly exothermic reactions can bring to a bad performance of the catalyst or to its fast deactivation. A possible solution is to use diluents, i.e., inactive ceramic bodies, tailored to mix intimately with the catalyst without affecting the fluid flow through the catalyst bed. The influence of the use of diluent materials on Fischer–Tropsch synthesis catalyst activity is here fully discussed.

The mechanism of atrazine degradation in aqueous phase was investigated under sonolysis at 20 kHz, ozonation, photolysis at 254 nm and photocatalysis in the presence of TiO2, employed either separately or in combination. Ozonation and photocatalysis induced atrazine de-alkylation, followed by slower de-chlorination, while direct photolysis at 254 nm produced very efficient de-chlorination. Simultaneous sonolysis had beneficial effects on ozonation and photocatalysis, especially by increasing the rate of photocatalytic de-alkylation, and no effect on the unimolecular photolytic de-chlorination of atrazine. Although complete atrazine mineralization could not be attained, because of the stability of the s-triazine ring toward oxidation, atrazine degradation and overall detoxification, as related to the disappearance of chlorinated by-products, proceeded at the highest rate when photolysis at 254 nm was combined with ozonation.

Dilute acetic acid (AA) streams (4.5–15%, w/w) were used in an extractive esterification with 2-ethyl-1-hexanol, exploiting the different solubilities of acetic acid and acetic ester in water. The main advantage of the process is the simultaneous water purification and production of an ester having a good commercial value. The new method proposed has the purposes to save the costs arising from the treatment of the waste water and utilize in chemical synthesis the acetic acid otherwise eliminated. The performed reaction is a three-phase system which Amberlyst 15 was used as acid catalyst in. It was clearly demonstrated that the reaction takes place in the organic phase and not in the aqueous one and a conversion of about 70% can be reached. A simplified mathematical model was also proposed.

Mass transfer is a rate limiting step in biodiesel production. Ultrasound can accelerate tremendously the mass transfer in both triglycerides transesterification and free fatty acid esterification by finely emulsifying reagents that are poorly miscible. We describe reactor configurations for both transesterification and esterification, with emphasis on the work published by the authors. Ultrasound in the esterification increases the mass transfer in raw oils at temperatures below 40 °C. The Eley–Rideal kinetic model of the esterification including the mass transfer resistance between the phases is in excellent agreement with the experimental data. The Rosett cell reactor combines acoustic cavitation and turbulence and transesterifies 90 % of the feedstock in 5 min, whereas it takes 90 min in a conventional batch reactor. Continuous and semi-continuous tubular reactors irradiated at a power density of 40 kW/cm3 converts 90 % of the oil in 10 min. A Sonitube® (Synetude) converts 90 % of the oil after a single passage in a continuous reactor. This corresponds to 18 s and a rate 300 times faster than the conventional process. Sonitube ® improves mass transfer substantially and is worthy of scaling up.

The separation of formic (C1), acetic (C2), propionic (C3), and n-valeric (C5) acids in binary water solutions has been studied using a reverse osmosis (RO) membrane pilot plant operating at different temperatures and pressures (usually 21 °C and 1.72 MPa). The RO membrane, which is composite, polyamide and spiral-wound, having a surface area of 2.6 m2, was fed by a solution of 0.5 M of C1, C2 and C3 acids and 0.146 M of C5. The pilot plant was used to simulate a cascade series of RO modules by recycling the permeate flux at the end of each semi-batch run. The influence on the retention coefficient, R, of molecular weight and molar volume, pKa of the different acids was determined. For acetic acid the influence of temperature (T) and transmembrane pressure (ΔP) was also studied, obtaining an inverse and direct good linear correlation for R vs. T and R vs. ΔP, respectively. The results are particularly interesting for acetic acid-water separation, which is an open question in industrial applications.

The degradation of 2-chlorophenol and of the two azo dyes acid orange 8 and acid red 1 in aqueous solution was investigated kinetically under sonolysis at 20 kHz and under photocatalysis in the presence of titanium dioxide particles, as well as under simultaneous sonolysis and photocatalysis, i.e. sonophotocatalysis. The influence on the degradation and mineralisation rates of the initial substrate concentration and of the photocatalyst amount was systematically investigated to ascertain the origin of the synergistic effect observed between the two degradation techniques. The evolution of hydrogen peroxide during kinetic runs was also monitored. Small amounts of Fe(III) were found to affect both the adsorption equilibria on the semiconductor and the degradation paths. Ultrasound may modify the rate of photocatalytic degradation by promoting the deaggregation of the photocatalyst, by inducing the desorption of organic substrates and degradation intermediates from the photocatalyst surface and, mainly, by favouring the scission of the photocatalytically and sonolytically produced H(2)O(2), with a consequent increase of oxidising species in the aqueous phase.

The valorisation of very low concentration of acetic acid (6%, w/w) was investigated by reacting with n-butanol and 2-ethyl-1-hexanol taking advantage of the different solubilities of acetic acid and acetic ester in water. The esterification of very diluted solution of acetic acid with alcohol is a reversible reaction and the conversion is greatly restricted by equilibrium limitation. Therefore, the peculiarity of the present method is to shift the reaction equilibrium towards the ester and not towards the reagents, thermodynamically favourite, because of the large amount of water. Different acid catalysts were tested in both homogeneous (sulphuric acid) and heterogeneous phase (polymeric resins and sulphated zirconia) to optimise the process efficiency.

Catalytic combustion with and without pre-catalytic actions (i.d., ionisation/ozonisation (I/O)) of tetracloromethane (CCl 4 ) over alumina-supported copper-chromite (Cu-Cr) and manganese (Mn) dioxide catalysts with and without the presence of hydrogen-rich compounds, i.e. n -hexane and toluene, was evaluated. Experiments were performed at conditions of lean carbon tetrachloride (CCl 4 ) concentration (from 500 to 3000 ppm V) in excess air, between 100 and 500 °C in a continuous reaction line at laboratory scale. n -Hexane and toluene were added to the feedstream in variable concentration, between 100 and 500 ppm V. Ionisation/ozonisation of pure CCl 4 streams and of streams of hexane or toluene admixtures showed the efficiency of the hydrogen donor role of the hydrocarbons on CCl 4 conversion. The tests of ionisation/ozonisation were performed at different residence times in the ionisation reactor and a rate equation with second-order in CCl 4 concentration was found to represent the ionisation process. Over Cu-Cr and Mn catalysts, both n -hexane and toluene improved the CCl 4 combustion when added at low concentration (ca. 300 °C) but inhibited it when they were present at high concentration (ca. 350 °C). Catalytic combustion assisted with ionisation process enhanced CCl 4 conversion at low temperatures in comparison with conventional catalytic combustion (e.g. 90% of 1000 ppm V of CCl 4 –hexane mixture was converted on Cu-Cr at 250 °C and 5000 h −1 by the combined actions of catalytic and ionisation processes). Selectivity to CO 2 was controlled on the two catalysts. Mn was more active but less selective than Cu-Cr catalyst. Various oxygenated and chlorinated by-products, in particular COCl 2 , were formed during ionisation of CCl 4 streams. By-products were greatly reduced and COCl 2 disappeared at 250 °C on catalysts.